a musical outfit specialising in clubby, electronica sounds i believe.
refers also to something that comes out of the blue, unexpectedly, as if from nowhere.
could refer to the left side of a sports field and the unusual-ness of a successful score from this side of the pitch...it's a guess.
or the left-h-s of the brain and the type of functions controlled therein.

whoah. that was a bit weird joe, straight out of leftfield. where do you get this stuff from, man?